WIP OpenSCAD grammar for tree-sitter

Based on https://files.openscad.org/grammar.xhtml

Supported features

• package
• statements
• statement
• include
• use
• comma_opt
• expressions_opt
• expressions
• expr
• lookup
• range_expression
• list_expression
• list_comprehension_elements
• list_comprehension_elements_or_expr
• let_clause
• for_clause
• if_clause
• function_definitions_opt
• function_definitions
• named_function_definition
• module_definitions_opt
• module_definitions
• named_module_definition
• function_call
• module_instantiation
• children
• child
• parameters_opt
• parameters
• parameter
• arguments_opt
• arguments
• argument
• assignments_opt
• assignments
• assignment